1995 850 GLT O2 Sensor closed loop fault

[moacyr]

Hello guys,

My 1995 Volvo 850 GLT is throwing 2 codes P0131 (Sensor Circuit Low Voltage, Bank 1 Sensor 1) and P0137. It is also throwing P0300 P1310 P0301 P0303 P0304 and P0305, but I guess it is misfiring due to a bad fuel trimming or a bad response from O2 sensor. Engine is hard to start when cold and sometimes when hot.

Recent changes:
Front O2 sensor (universal)
Spark plugs (bosch)
Fuel filter, air filter

The engine only misfires when engine is completely warmed up (when driving for about 25 miles) or when there is more than 3 engine starts, also when hot.

My question is: How to solve that O2 sensor problem? (if it is the real problem)

I've done some reading with OBD, it follows below

There is only variation on the output VOLTAGE and Short Term Fuel Trimming when the loop is closed (FAULT)

When the loop is closed, there is output from O2 sensor and STFT operates. When the loop is open, there is no response either from O2 sensor and STFT

With the car stopped, and accelerating at around steady 1800rpm, the loop is closed and there is normal response either from sensor and STFT

[Ozark Lee]

Was the replacement universal oxygen sensor a Bosch? Anything but the OEM equivalent Bosch with the factory connector has historically been trouble but I think many of the problems with the Bosch universal have actually been in the spice box. Sensors other than Bosch have rarely, if ever, worked.

...Lee

[moacyr]

Yes, it is a Bosch universal sensor.

[draser]

Misfiring is caused by a mixture issue, and o2 sensor merely responds to what it sees. I'd look at trims and go from there. Now if system doesnot stay in closed loop you may have a defective sensor. However, since car's hard to start I'd check ECT first.

[moacyr]

Misfiring is caused by a mixture issue, and o2 sensor merely responds to what it sees. I'd look at trims and go from there. Now if system doesnot stay in closed loop you may have a defective sensor. However, since car's hard to start I'd check ECT first.

how can I look at trims? I dont know how to test the sensor in the car, to check its effectiveness.

[draser]

I'd use a scanner that can read live data, that will give you fuel trims, engine temperature and o2 operation. Also measure resistance of ECT when cold and hot.

[moacyr]

I'd use a scanner that can read live data, that will give you fuel trims, engine temperature and o2 operation. Also measure resistance of ECT when cold and hot.

So I did. Short term fuel trim locked on 0%. Long term fuel trim locked on 25%. Temperature is OK (90°). Idle MAF 5g/s (is that normal?). Idle throttle position sensor 12% (was not supposed to be 0%?)

ECT resistance: seems to be according with temperature.

Updates:
Did a research on PCV sistem, seems OK. Vapour still coming out from dipstick
Changed manifold gasket.
Cleaned EGR
Cleaned throttle body

[misha]

Yes, it is a Bosch universal sensor.

That's a problem.

[moacyr]

Yes, it is a Bosch universal sensor.

That's a problem.

Bosch P/N: 0 258 003 222
As according to Bosch Catalog

[misha]

It isn't really a problem because it's universal Bosch sensor.The problem is laying in connection to original connector.It can't be soldered,it must be properly crimped and properly sealed.
Sensors can be made of Titanium and Zirconium.They are two different types of sensors.Titanium works in the way that it sends resistance value to ecu and zirconia one sends voltage.They are visually very different,especially the "head" of the sensor and the wires have different colors.
Our cars use Zirconia 02 sensor but there is just a small number of 850(s) which use Titania one.My guess is that those are the ones with Siemens management.They usually have Yazaki clusters.